The present invention is related to a light-emitting warning device of a safety helmet. The light-emitting warning device is firmly installed and located on an outer face of the safety helmet to emit light at high efficiency within a wide range so as to provide enhanced lighting warning effect.
FIG. 1 shows a conventional safety helmet with a warning strip 5 disposed along a circumference of the safety helmet. The warning strip 5 includes a flexible transparent strip body 50 and multiple warning lights (or LEDs) 51 uniformly distributed in the strip body 50. The warning lights 51 are controlled by a control circuit to light and flicker around the safety helmet so as to provide warning effect in the dark. Such warning strip 5 is manufactured at high cost and used with high power consumption. Therefore, it is necessary to frequently replace the cells. Moreover, the warning strip 5 has a considerable weight so that a user of the safety helmet will bear greater load. Therefore, it is inconvenient and not economical to use such safety helmet. In addition, the warning lights 51 emit light simply in specific directions. In the case that the number of the warning lights 51 is too small, the lighting range will be insufficient or unapparent. Therefore, the safety helmet must be equipped with a considerably large number of such warning lights to achieve apparent lighting effect. As a result, it is necessary to remove a considerable part of the safety helmet main body for providing a space in which the warning lights can be installed. Under such circumstance, the structural strength of the helmet will be deteriorated to affect the safety effect provided by the helmet.
FIG. 2 shows another conventional safety helmet having an inner shell 6. The inner shell 6 is formed with an annular groove 61 in which a light guide strip 62 and LEDs 63 are disposed. An upper shell 64 and a lower shell 65 are fitted on outer face of the inner shell 6. The rims of the upper and lower shells 64, 65 are inlaid in the groove 61 to fix the light guide strip 62. The inner shell is further formed with a cavity 66 in which a cell assembly 67 is received. In addition, a control circuit unit 68 with a switch is fixed between the inner shell 6 and the lower shell 65 for driving the LEDs 63 to emit light. The light guide strip 62 serves to guide the light throughout the periphery of the safety helmet. Such structure is able to lower power consumption. However, the wall of the annular groove 61 in which the light guide strip 62 is inlaid can hardly reflect the light. Moreover, the rims of the upper and lower shells 64, 65 serve to hold the light guide strip 62 in the annular groove 61. It is quite difficult to assemble the light guide strip 62 with the helmet in this manner so that the manufacturing cost of the helmet is increased and the competitive ability of the product is affected. In addition, it often takes place that the light guide strip 62 is not truly held in the annular groove 61. As a result, in use, the light guide strip 62 is likely to drop out of the groove 61 and damage or even hit a rider's face or tangle with the rider's neck. This is extremely dangerous. In order to solve this problem, the open side of the channel 61 is generally formed with a width smaller than the diameter of the light guide strip 62, whereby the light guide strip 62 can be inlaid in the annular groove 61 without dropping out. However, such measure will inevitably reduce the area of the light guide strip 62 exposed to outer side. As a result, the intensity and scattering area of the light emitted from the light guide strip 62 will be seriously affected. Also, the light guide strip 62 is totally positioned on outer circumference of the inner shell with the connection sections of the control circuit unit exposed to outer side. Consequently, external water and dust tend to infiltrate into the control circuit unit to wet the light guide strip 62. This will affect the light diffusion effect of the light guide strip 62.
U.S. Pat. No. 6,007,213 discloses a safety helmet including an inner shell formed with a recessed channel. A fiber optic cable is received in the recessed channel. Two end sections of the fiber optic cable are connected to a light source via two connectors respectively. The light source is connected to a power source via a switch. The inner shell is covered by an outer shell. The outer shell is formed with a transparent area corresponding to the extending position of the fiber optic cable. The light generated by the light source is guided by the fiber optic cable and emitted outward through the transparent area of the outer shell. In such structure, the fiber optic cable and relevant components are protected by the outer shell. Therefore, the safety helmet has higher reliability and longer using life. However, the recessed channel is positioned on the inner shell, while the transparent area is formed on the outer shell. Therefore, in practical development and production, the inner and outer shells must be manufactured with high precision. Otherwise, after assembled, the recessed channel may be misaligned from the transparent area. In this case, the light emitted from the fiber optic cable will be interrupted by those areas other than the transparent area. Accordingly, both the poor transparence and the error in the assembling process will affect the light diffusion effect of the fiber optic cable. As a result, the ratio of defective products will increase due to difficulty in processing. This will lead to increment of manufacturing cost.